The present invention relates to a heat exchanger adapted for use as a hot water radiator for a car heater, or the like, and particularly to a heat exchanger of such type, which has no brazed portion.
Generally, a heat exchanger of this kind includes a plurality of tubes extending through a number of parallel plate fins, wherein a secondary fluid such as air streams over the plate fins to heat a primary fluid such as water flowing in the tubes by heat exchange with the latter.
The tubes have end portions connected to opposed fluid tanks to which are connected pipes which communicate with an associated fluid circuit. In such heat exchanger, the joints of parts such as those between the tubes and the tanks should have sufficient fluidtightness as well as shock resistance.
To meet with such requirements, according to U.S. Pat. No. 3,583,478 for instance, a heat exchanger has been proposed which includes two tanks each formed by a manifold or end plate and a cap-like header, said manifold comprising a sheet which is made of a metal plate and includes annular flanges defining openings and a sheet-like gasket having annular flanges defining openings corresponding to the openings of said sheet and urged against said sheet with the flanges thereof internally lining the flanges of said sheet. Tubes have end portions sealingly inserted into the annular flanges of said gasket, said end portions being expanded to have a diameter larger than the respective remaining portions of the tubes to crimp the gasket between the tubes and the manifold. Each manifold has a peripheral flange bent around the peripheral flange of the associated header for sealed engagement therewith.
In such proposed heat exchanger, there is a problem that with a long time of use the thermal fluid (e.g., cooling water) may permeate through the gasket, usually made of rubber and internally lining the manifold, which may cause the manifold to rust. Furthermore, the peripheral joint portion of the manifold and header of the tank obtained by crimping the peripheral edge of the manifold projects outwardly of the heat exchanger body so that the whole size of the heat exchanger is necessarily large.